Fairchild's Advanced Power Load Switches Introduction

Foreword:

What Are Load Switches?

Integrated load switches are integrated electronic relays used to turn on and turn off power rails. Most basic load switches consist of four pins for input voltage, output voltage, enable, and ground. When the device is enabled via the ON pin, the pass FET turns on, thereby allowing current to flow from the input

pin to the output pin, and power is passed to the downstream circuitry.

Integrated load switches are electronic relays that can be used to turn on and turn off power supply rails in systems. Load switches offer many other benefits to the system and can include protection features that are often difficult to implement with discrete components. There are many different applications where

load switches can be used including, but not limited to:

• Power Distribution
• Power Sequencing and Power State Transition
• Reduced Leakage Current in Standby Mode
• Inrush Current Control
• Controlled Power down

1.Why use load switches

Power management plays an increasingly important role in consumer electronics and mobile electronics.At the system level, the advanced load switch by sequence control, standby power, input voltage sag, it ran down/over-voltage protection/over-current protection, over temperature protection.

You could use a single FET, but there are several advantages to using a load switch IC.Voltages higher than the micro voltage can be switched. (That can also be done by using 2 transistors. )

The load switch has inrush current limiting built in. This can be done with discrete components as well, but requires more engineering.More often than not, load switches have monitoring, such as power good or overcurrent outputs, etc.

Tolerance analysis is easier when that entire circuit is on one die with guaranteed data on its performance.

2.Fairchild's rich load switch product portfolio
Fairchild's advanced integrated load switch product line supports the latest mobile industry and consumer electronics devices.IntelliMAX ™ products series will traditional MOSFET and a set of protection, control, and fault monitoring function, the combination of promoting power management to realize high efficiency and reliability, while minimizing circuit board space.Applications include portable equipment, set-top boxes, DVD players and consumer electronics, inventory management and portable terminal device, the keyboard and buttons, GPS system and wireless data systems, low voltage industry and communication, medical equipment, calculation, and hard disk drives.
Fairchild's voltage swing rate controls load switches to control MOSFET conduction speed, helping to reduce input voltage sag and avoid triggering under-voltage latches.Over-current protection load switch allows the user to set the current limit, prevent the downstream power supply/load or among three protection options - constant current power supply, turn off or restart automatically, over-current overheating/too much stress.If overvoltage events are detected at the output, the overvoltage protection load switch will turn off MOSFET to prevent the downstream power/load from suffering abnormal voltage stress.

The PowerMux switch, which controls MOSFET with a voltage swing rate, can switch between two inputs to determine the source of downstream power/load.

3.The design can be completed in a minute using the load switch design tool

Fairchild provides more than 100 advanced load switches to meet various requirements for different applications.Manually select the appropriate switch is time consuming and calculate the component values is cumbersome, especially when it comes to requirements set current, and under the condition of fault from three options (current source on/off/retry) choose the over-current protection switch.Special attention should be paid to the output capacitor value when using the shut-off feature to avoid early shut-off, as too large capacitors may trigger overcurrent limits during start-up.The load switch design tool takes all factors into account and provides all recommended component values for safe operation.Users can complete the design in a single page, from entering basic input, output requirements, trying different available switches, generating BOM files, to purchasing load switches/requesting load switches samples.The available part tables, schematics/component values, and BOM are dynamically updated after each specification change.The whole design can be finished in a minute.

4.Related Load Switch Overview：ON Semiconductor FPF2495 Load Switch

ON Semiconductor FPF2495 IntelliMAX Load Switches are advanced load-management switches which  target applications requiring a highly integrated solution. FPF2495 disconnects loads powered from the DC power rail (<6V) with stringent off-state current targets and high load capacitances (<100uF). The FPF2495 consists of a slew-rate controlled low-impedance MOSFET switch (100mΩ maximum) and integrated analog features. The slew-rate controlled turn-on characteristic prevents inrush current and the resulting excessive voltage droop on power rails. FPF2495 has over-voltage protection and over-temperature protection.

Features
VIN: 2.5 V~5.5 V
28 V Absolute Ratings at VOUT
Current Capability: 2.0 A
Adjustable Current Limit: (Typ.) 0.1 A~1.5 A with 10% Accuracy
RON: Maximum 100 mΩ at 5 VIN and 1 A
Output OVP: Min.=5.6 V, Typ.=5.8 V, Max.=6 V
No Output Discharge During Off State
Open-Drain OVP on FLAGB
Thermal Shutdown
Under-Voltage Lockout (UVLO)
True Reverse-Current Blocking (TRCB)
Logic CMOS IO Meets JESD76 Standard for GPIO Interface and Related

Applications
Media Tablets
Storage & Peripherals
Mobile Handsets
Wireless LAN Card & Broadband Access
PMP/MP3 Players

More information and the download address of datasheet ，Link Address

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